To perform deposition by a CVD scheme or the like in electronic device manufacturing including a semiconductor manufacturing process, as a precursor of organic metal, for example, a liquid for deposition with high purity such as TDMAT (Tetrakis (Dimethylamino) Titanium) is used. This liquid material (such as TDMAT) may be accommodated in a raw material container. To the raw material container, a gas introduction pipe and a discharge pipe may be connected. From the gas introduction pipe, an inert carrier gas such as He or N2 may be fed to pressurize the inside of the raw material container, and the liquid material accommodated in the raw material container may be supplied via the discharge pipe to a semiconductor manufacturing apparatus.
In a midway of this discharge pipe, for example, a gate valve for controlling supply of the liquid material to the semiconductor manufacturing apparatus is provided. Also, on a secondary side (semiconductor manufacturing apparatus side) of this gate valve, a purge pipe for introducing a purge gas to a supply line to the discharge pipe and the semiconductor manufacturing apparatus is branched. In a midway of the purge pipe branched from the discharge pipe, a purge valve which is normally closed and opened at a purge process to introduce a purge gas is provided. Also, on a downstream side of these discharge pipe, gas introduction pipe, and purge pipe, a connector is attached.
With the discharge pipe and the gas introduction pipe being connected to the raw material container, the raw material container can be separated from the supply line to the semiconductor manufacturing apparatus and so forth.
When the raw material container becomes empty or when a liquid material of another type is supplied to the semiconductor manufacturing apparatus, prior to removal of the raw material container from the semiconductor manufacturing apparatus, a purge process is performed to remove the liquid material remaining inside the discharge pipe and the supply line. At the purge process, the gate valve is closed, and the purge valve provided to the purge pipe is opened, thereby introducing the purge gas from a purge gas supply source to the purge pipe. The purge gas flows from the purge pipe via a branching part through the supply line including the discharge pipe, and is discharged outside the semiconductor manufacturing apparatus. By this supply of the purge gas, the liquid material remaining inside the discharge pipe and a liquid-phase line can be removed.
However, in the valve for the raw material container in this conventional structure with a combination of pipe lines (pipe) and valves, it is required to branch the purge pipe at an upper portion of the gate valve provided to the discharge pipe. Therefore, the structure is such that the gate valve and the purge valve are stacked in a vertical direction. In a pipe line between the gate valve and the purge valve, a retaining part (dead volume) of the liquid material is formed. Thus, at the purge process, while removal of the liquid material remaining in the pipe line can be performed in a relative short time, removal of the liquid material remaining in this dead volume is difficult, and a time required for the purge process is long.
In particular, when the liquid material for use is a chemical substance with a low vapor pressure such as TDMAT, to completely remove the liquid material remaining in this retaining part, a long-time purge process is required, and requiring a long purge process time decreases an operating rate of the semiconductor manufacturing apparatus, and becomes a large factor in inhibiting productivity.
Also, if the purge process is insufficient, the liquid material remains in the dead volume. Therefore, when the raw material container having a liquid material of a different type accommodated therein is connected to the semiconductor manufacturing apparatus thereafter to start supply of that liquid material, the components of the liquid material remaining in the supply line is mixed into that liquid material, and the polluted liquid material is supplied to the semiconductor manufacturing apparatus although a liquid material with high purity or ultrahigh purity is required.
In Japanese Patent No. 4125633 suggested as a valve for a container of this type, in order to allow a purge process to be performed in a short time even when a high-purity liquid material with a low vapor pressure is used, a valve manifold for a raw material container configured with a low dead volume has been known. In this valve manifold, diaphragm surfaces of two diaphragm valves are opposed to each other to be disposed in a manifold block, and a flow path coupling port openings of these valves and a flow path communicating with port openings of the respective valves from outside are provided in the manifold block.
Thus, unlike the conventional valve for the raw material container, a dead volume due to the structure with a combination of pipe lines (pipes) and valves is not formed in the flow path in the manifold block, and a wet surface area of the flow path formed in the manifold block can be minimized. Therefore, a purging process can be completed in a significantly shorter time than a purging time conventionally required for a liquid material with a low vapor pressure.
When a purge process on a flow path in this valve assembly mounted at an upper portion of the raw material container is performed, a valve on a side leading to the raw material container is opened, a valve on a side leading to a vacuum source is closed, and a purge gas is introduced from a purge-gas introduction source via a liquid-phase line branched from a flow path connecting the valves together to push back a liquid material remaining in the valve assembly to the raw material container. Then, the valve on the side leading to the raw material container is closed, the valve on the side leading to the vacuum source is opened, and the purge gas is introduced again via the liquid-phase line to perform a purge process in the flow of the assembly.